Sift the flour. Knead the softened butter, sugar, vanilla sugar, egg, lemon zest, flour and a pinch of salt together. Wrap the dough in cling film and place in the refrigerator for 1 hour. Knead the dough on a lightly floured work surface and roll out 5mm thick. Cut out with the desired shapes. Chill the punched biscuits in the refrigerator for 30 minutes. Preheat the oven to 180 ° C top / bottom heat. Bake the cookies on a baking tray lined with silicone baking mats or parchment paper for 6-10 minutes. Let cool down well after baking.

For the royal icing: beat the egg whites until stiff. Sieve the powdered sugar onto the egg white. Gradually stir in until you get a smooth mixture. The mass is now very solid. Now you can carefully add liquid and stir again and again and test whether the consistency is right for your purposes. Color the mass as you like, I always use food gel colors